What Are the Best Tips for Air Conditioning Troubleshooting?

Wall-mounted, cabinet, or window-type air conditioners that have dirty plugs (such as catkins and dust) outside the evaporator and condenser will significantly reduce the cooling effect and even appear non-refrigerating. Some users often think that this is a lack of fluorine. Send it to the repair department for repair. In fact, when a layer of dirt is attached to the condenser, the condensation effect becomes worse, which will seriously affect the refrigeration. Once dirt is generated on the surface of the evaporator, the cooling capacity cannot be effectively exerted, so the refrigeration equipment cannot work normally. Our repair department often encounters such repair cases. Of course, once the fault is cleaned up, the failure of the refrigerating and air conditioning is eliminated immediately.

Air conditioning failure

First, the air conditioner signal (control) transformer will cause the whole machine to stop working if it is damaged.

The basic methods for judging the common faults of domestic air conditioners are: see, listen, touch, measure and analyze.

1. Look: Carefully observe the working conditions of each component of the air conditioner, focusing on the three parts of the refrigeration system, electrical system, and wind system to determine whether they are working properly.

(1) Refrigeration system: observe whether there are cracks, breakages, frost and dew on the pipes of the refrigeration system; whether there is friction between the refrigeration pipes, the pipes and the housing, especially the refrigerant pipes Welding place, whether there is leakage at the joint connection, oil leakage (a certain amount of refrigerating machine oil in the refrigeration system) can be found at any leakage, you can also use a clean soft cloth, soft paper to wipe the joint between the pipe welding and the joint, and observe whether there is Oil stains to determine if a leak has occurred.

(2) Electrical system: observe whether the fuse of the electrical system is blown, whether the insulation of the electrical wires is intact, whether the circuit board is broken, and whether the connection is loose. In particular, whether the electrical connection is in good contact, wiring screws and connectors are easily loosened and cause poor contact.

(3) Ventilation system: observe whether the air filter, heat exchanger coils and fins have accumulated excessive dust; whether the air inlets and outlets are open; whether the fans and blades are operating normally; whether the wind is normal.

2. Listen: Listen to the air conditioner compressor to check whether the sound of the air conditioner compressor is normal, whether there is any abnormal sound, whether there is noise in the fan operation, whether the noise of the air conditioner is too large, etc. During operation, the air conditioner has slight vibration and low noise under normal conditions, generally below 50DB. If vibration and noise are excessive, the possible causes are:

(1) Improper installation. Such as the size of the bracket does not match the unit, the fastening is not tight, or no damping rubber, foam plastic pads, etc., can make the air conditioner in operation increase vibration and noise. This is especially noticeable when starting and stopping.

(2) The compressor is not vibrating normally. Poor mounting of the base, uneven feet, poor installation of shock-proof rubber or shock-proof spring, or poor shock-proof effect. If there is a malfunction inside the compressor, such as broken valve discs, liquid shock, etc., it will also make abnormal sounds.

(3) The fan hits. Poor installation or deformation of fan blades can cause collision noise. The fan may collide with the wall shell and the chassis. The axis of the fan will move, and the blades will lose their balance, and they will also make an impact sound. If there is a foreign object in the fan, the blades will also collide with it.

3. Touch: Touch the relevant parts of the air conditioner with your hands to feel the hot and cold, chatter and other conditions, which is helpful to judge the nature and location of the fault. Under normal circumstances, the temperature of the condenser gradually decreases from top to bottom, and the temperature in the lower part is slightly higher than the ambient temperature. If the entire condenser is not hot or the upper part is slightly warm, or if it is hot, but the temperature of the two adjacent pipes is significantly different, it is abnormal. Evaporator Under normal circumstances, placing your fingers soaked in water on the surface of the evaporator will feel cold and sticky. The capillary at the dryer and outlet should have a warm feeling under normal conditions (slightly higher than the ambient temperature, which is basically the same as the temperature of the pipe at the end of the condenser). Etc. are not normal. The suction pipe at a distance of 200mm from the compressor should, under normal circumstances, be about the same as the ambient temperature.

4. Measurement: In order to accurately determine the nature and location of the fault, instruments and meters are often used to check and measure the performance parameters and status of the air conditioner. If you use a leak detector to check whether there is refrigerant leakage; use a multimeter to measure the power supply voltage, the current to ground and the running current of each terminal meet the requirements, and the air conditioner controlled by the computer should also measure whether the potential at each control point is normal.

5. Analysis: Most of the results obtained through the above-mentioned inspection methods can only reflect a certain local state. The various parts of the air conditioner are related to each other and affect each other. There may be multiple causes for a failure phenomenon, and multiple failures for one cause. Therefore, a comprehensive comparative analysis of local factors is required to comprehensively and accurately determine the nature and location of the fault.

1. Observe the working conditions of the internal and external machines: such as the display of the indicator board, whether the internal machine is working, whether the wind speed output is normal, and whether the external fan and compressor are running, so as to determine whether it is an electrical problem or a system problem that is not cooling.

2. Test various data of air conditioner:

A. Leakage of air conditioner. Generally, the continuous drip air conditioner of the internal machine is normal, but it can only be used as a reference value due to the influence of ambient humidity and temperature.

B. The temperature difference between the air inlet and the air outlet. The normal temperature difference between the air inlet and outlet should be 12-14 degrees, but it will also be affected by the ambient temperature and wind speed.

C. Measure the pressure of the system pipeline. Generally, the low-pressure pressure is 0.45Mpa-0.50Mpa during cooling and the high-pressure pressure is 1.8Mpa-2.2Mpa during heating. However, the pressure is affected by the ambient temperature. The higher the temperature of the air inlet, The higher the exhaust pressure, the higher the condensation temperature, and vice versa; the larger the air conditioning load, the higher the suction pressure, and the higher the evaporation temperature (the normal evaporation temperature of the evaporator is between 5-7 degrees).

1. Refrigeration system blockage: It often occurs at the capillary and drying filter, because these two places are the narrowest places in the system. There are three common causes of blockage: dirty blockage, ice blockage, and welding blockage.

A. Dirty blockage usually occurs at the inlet of the capillary tube. It is due to the dirt in the system (such as welding slag, rust scale, oxide scale, etc.) blocking the pipeline. Gently tapping the capillary tube during inspection may temporarily return to normal. In addition, the location and nature of the blockage can be judged from the condensation and frost on the surface of the pipes and components, as well as the pressure recovery speed time during shutdown.

B. Ice blocking generally occurs at the exit of the capillary. It is because the system contains moisture, which is condensed into small ice particles due to the sudden vaporization and cooling at the exit of the capillary. It is blocked at the exit of the capillary if you judge. The normal or improvement indicates ice blockage, or the machine can be cooled for a while after the air conditioner is turned off, and the ice blockage usually occurs on a newly installed or newly repaired air conditioner.

C. Welding plugs generally occur at the welding place of capillaries. The phenomenon is similar to dirty plugging and ice plugging, and most of them occur on new installations.

2. Leakage of refrigeration system: The carrier of air-conditioning cooling and heating is refrigerant. If there is a leak in the system, if the refrigerant leaks, the air-conditioning has poor or no refrigeration, and the places where the air-conditioning leaks are mainly concentrated on the welding heads of the two appliances. , Capillary welds, compressor suction and exhaust pipes, bell mouth, copper and sodium cracks, connection pipes, etc., when you want to check, you can first carry out visual inspection, focus on the inspection of the joints of the connection pipe, leaks generally have oil stains.

3, four-way valve failure, usually occurs during heating, the four-way valve sucks badly, cross-gas or stuck, causing poor heating performance, when judging whether the four-way valve is on and off and listen to whether the suction is good During maintenance, the four-way valve can be repeatedly energized or lightly tapped to reset it.

4. The check valve is faulty. The check valve is directly connected during cooling, but the refrigerant must pass through the auxiliary capillary during heating. When the check valve is not tightly sealed or the auxiliary capillary is blocked, the heating is affected. If the air conditioner has normal cooling but poor heating, check the check valve after removing the problem of the four-way valve.

1.Pressure gauge

Refrigerant leakage is a common failure of air conditioners. In order to test whether the amount of refrigerant in the system is sufficient, pressure gauges are commonly used. Pressure gauges are commonly used detection tools in Freon refrigeration systems. Its shell diameter ranges from 60mm to 250mm and has a variety of specifications. The range of vacuum pressure gauge suitable for the air-conditioning refrigeration system is 0.1MPa 2.5MPa,

Pressure gauges are often used with three-way repair valves. Turn the three-way repair valve knob clockwise to reduce the valve hole. When the knob is turned clockwise to the end, the corresponding piping is cut off from the outdoor unit. When the knob is turned counterclockwise, the valve hole Enlarged, the corresponding piping is connected to the outdoor group gas path, the refrigeration system and the pressure gauge on the three-way repair valve are always connected, regardless of the position of the knob. Through cooperation with the three-way repair valve switch, the refrigeration system can be realized Evacuate, charge refrigerant and test pressure.

2.Expansion device

When two copper pipes are docked, one copper pipe needs to be inserted into another copper pipe. At this time, the inner diameter of the end of the inserted copper pipe often needs to be expanded so that the other copper pipe can be inserted in a consistent manner. Only in this way can the two copper pipes be welded firmly, and leakage is not easy to occur. The function of the pipe expander is to expand the copper pipes of different specifications according to the needs. When expanding a pipe, first place the annealed copper pipe into the corresponding hole diameter of the pipe clamp. The length of the copper pipe protruding from the pipe clamp varies with the diameter of the pipe. For a copper pipe with a large pipe diameter, the length of the expanded pipe should be large. For a copper pipe with a small diameter, the length of the expanded pipe is smaller. For a copper pipe of 8, the length of the expanded pipe is generally about 10mm. Tighten the nuts at both ends of the pipe clamp to firmly clamp the copper pipe. The diameter of the tube expander, slowly rotate the screw of the tube expander clockwise to expand to the required length, the tube expander

3.flare

The flaring device is used to expand the bell mouth of the copper pipe, so that the indoor and outdoor units of the split air conditioner can be connected by piping. When expanding, first anneal the copper pipe with the connection nut, and then place the copper pipe into the pipe clamp accordingly Within the diameter of the copper pipe, the height of the exposed copper clamp is one-fifth of the diameter of the copper pipe. Tighten the nuts at both ends of the clamp, press the cone head of the flaring jack on the pipe mouth, and slowly rotate the screw clockwise. Squeeze the mouth into a bell mouth

4, pipe cutter

When repairing and installing air conditioners, pipe cutters are often used to cut copper pipes of different lengths and diameters. Pipe cutters have different specifications.

When cutting the copper pipe, the copper pipe must be placed between the two rollers of the pipe cutter, and the knife button should be rotated clockwise, and the copper pipe should be clamped between the knife and the roller, and then rotated while turning the knife button. Rotary cutting knife for copper pipe. When rotating the knife, the force must be even and soft. Otherwise, the copper pipe may be deformed. After the copper pipe is cut off, the burr on the edge of the pipe shall be removed with a reamer to prevent it. Copper filings enter the refrigeration system.

5, pipe bender

The pipe bender is a tool used to change the shape of the copper pipe and process the copper pipe into the required shape. The pipe bender has a variety of sizes and is suitable for bending copper pipes with a radius of less than 20mm. Place the annealed copper pipe into the wheel groove of the pipe bender, lock the pipe clamp hook, and slowly rotate the handle until the desired angle,

6. Gas welding equipment

The refrigeration system of the air conditioner mostly uses copper pipes. Gas welding is used for maintenance. Traditional gas welding equipment uses oxygen and acetylene gas to mix and ignite to produce a high-temperature flame. Now more liquefied petroleum gas is used and oxygen is used to support the liquefied gas welding machine For welding of refrigeration system pipelines, gas welding equipment is mainly composed of 3 parts: gas cylinder, connecting hose and welding torch.

7, clamp meter

Clamp meter is a widely used measuring instrument. It is the most commonly used tool for electrical equipment troubleshooting. It can measure AC or DC voltage, AC current, resistance, etc.

Measure AC and DC voltage

First transfer the transfer switch to ACV or DCV, and select a range greater than the measured voltage, and then insert the red and black test leads into the socket of the power supply socket under test. The number displayed on the panel is the measured value. The voltage value and AC voltage have no fixed polarity, so the test leads of the clamp meter can be used regardless of the positive and negative poles. When measuring DC voltage, you should rotate the transfer switch to the DC voltage range (DCV), and pay attention to selecting a range greater than the measured voltage, and also make sure the polarity of the measured voltage. When measuring, connect the red test lead to the positive voltage. The black test lead is connected to the negative voltage. If the polarity of the test lead is wrong, the clamp meter may be damaged.

Measure AC current

Rotate the transfer switch to a suitable range of alternating current (ACA). During the measurement, as long as the measured wire is clamped in its clamp-shaped mouth, using the principle of electromagnetic induction, the display screen can indicate the strength of the current in the wire.

, measuring resistance

Rotate the transfer switch to a suitable range. Before the measurement, connect the two test leads directly (short-circuited). At this time, the reading on the display should be 0 and a beep sounds. If the displayed number is not 0, it means that the clamp meter is damaged or the power Insufficient. When measuring, connect the test leads to the two ends of the measured resistance, and the number displayed on the screen is the measured resistance value.